XWiki Collaboration Suite (XCS) is used across the whole OW2 organization and the OW2 community. XCS is also one of the key components on top of which OW2 is implementing its Quality Program Platform. XCS addresses two types of issues: collaboration related issues, and application development ones. On the collaboration side, XWiki makes it seamless to create and evolve collaborative knowledge bases. On the development side, XCS provides a rich API and a large number of extensions speeding up considerably the development of powerful Web applications.